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1
Zhang, Rongfei, e Ziyan Zhao. "Giant Trees Exhibited Great Cooling Effect in Residential Area Southwest of China". Forests 13, n. 9 (19 settembre 2022): 1516. http://dx.doi.org/10.3390/f13091516.
Abstract (sommario):
In recent years, extreme weather has become more and more frequent. The extreme heat in summer is a serious threat to human health. Chongqing is one of the hottest cities in China, and the high temperature in summer can cause skin cancer and heat stroke. Green plants in residential areas play a great role in cooling down air temperature. However, there are no accurate numerical references for which plants have a better cooling effect. Therefore, seven species of trees with the highest planting rate were selected in seven residential areas as research objects in this study. By measuring the temperature under the trees and related control factors, this study was conducted to clarify the following: (1) Which species of tree has the best cooling effect? (2) Whether tree species and size matter with the cooling effect. (3) What are the controlling factors and principles that affect the tree cooling effect? The results showed that: (1) Giant trees have the best cooling effect. (2) The cooling effects of Ficus virens, Camphor tree, and Ficus macrocarpa were significantly better than the other four species of trees. (3) The high rate of water replenishment in plants gives giant trees a greater cooling effect. This study is of great practical significance to the selection of plants in the green belt of residential communities, and has great theoretical significance to understand the principle of the plant cooling effect.
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Feliksik, Edward, e Sławomir Wilczyński. "The Effect of Climate on Tree-Ring Chronologies of Native and Nonnative Tree Species Growing Under Homogenous Site Conditions". Geochronometria 33, n. -1 (1 gennaio 2009): 49–57. http://dx.doi.org/10.2478/v10003-009-0006-4.
Abstract (sommario):
The Effect of Climate on Tree-Ring Chronologies of Native and Nonnative Tree Species Growing Under Homogenous Site ConditionsDendroclimatic studies were carried out in the experimental stands composed of many tree species situated in the Polish part of the Baltic sea-coast. Increment cores were taken from a 100-years old trees of 2 native species: Norway spruce (Picea abies (L.) Karst.), and Scots pine (Pinus sylvestrisL.) and 3 nonnative species: Douglas fir (Pseudotsuga menziesii(Mirb.) Franco), Sitka spruce (Picea sitchensis(Bong.) Carr.) and Silver fir (Abies albaMill.). Thirty trees of each species were cored. The relationships between the diameter increment and the thermal and pluvial conditions during the period from 1925 to 2005 were analyzed on the basis of standardized tree-ring chronologies and climatic data. It was found that precipitation and temperature of the growing season and months preceding that season affected the annual diameter increment of all investigated tree species. The current year winter and early spring temperatures as well as February and August precipitation had a similar effect on the variation of diameter increment of trees. On the other hand thermal and pluvial conditions of the current year June differentiated the increment rhythm of individual species. A very strong negative effect on diameter growth of trees was observed in the case of winter and early spring frosts. Norway spruce turned out to be a species most resistant to low temperatures. The investigated tree species, especially Norway spruce, was susceptible to water deficiency in the soil during spring and summer. In the case of Scots pine a high precipitation in June stimulated its growth. The diameter increments of Douglas fir, Sitka spruce, Scots pine, and Silver fir were more strongly connected with air temperature than with precipitation. So called all-species chronology of tree-ring width, constructed during this study, permitted to verify the factors having a similar effect on growth response of the investigated tree species. It reflected the mutual characteristics of diameter increments of trees of various species.
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Cysneiros, Vinicius Costa, Allan Libanio Pelissari, Tatiana Dias Gaui, Luan Demarco Fiorentin, Daniel Costa de Carvalho, Telmo Borges Silveira Filho e Sebastião do Amaral Machado. "Modeling of tree height–diameter relationships in the Atlantic Forest: effect of forest type on tree allometry". Canadian Journal of Forest Research 50, n. 12 (dicembre 2020): 1289–98. http://dx.doi.org/10.1139/cjfr-2020-0060.
Abstract (sommario):
Tree height is one of the most important variables for quantitative assessment of forest stocks, but it is difficult to directly measure. Such allometric relationships of trees can vary between geographical regions, however, mainly due to climatic, edaphic, and floristic gradients. Based on the hypothesis that different forest types influence the generic modeling of tree height–diameter relationships on geographical scales, this study aimed to (i) fit equations to estimate tree height in Atlantic Forest types in the state of Rio de Janeiro, Brazil; (ii) compare efficiency and precision between generic and specific equations for forest types; and (iii) test the effect of different forest types and species on the height–diameter relationship. Four allometric models were tested for all forests (generic) and three main forest types (specific). Effects of tree size, forest types, and species on tree height estimation were analyzed using multiple linear models and mixed-effect linear models. A significant effect of forest type and species on tree height was seen, showing the need to apply local specific equations to minimize the effects that are not captured by generic equations. Differences in tree allometry between forest types were associated with temperature, rainfall, soil, and forest structure. These results confirm the effect of the local environment on the height–diameter relationship of trees as found over large scales in tropical forests.
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OLIVAL, Alexandre de Azevedo, Saulo Eduardo Xavier Franco de SOUZA, Jozivaldo Prudêncio Gomes de MORAES e Mariana CAMPANA. "Effect of Amazonian tree species on soil and pasture quality in silvopastoral systems". Acta Amazonica 51, n. 4 (dicembre 2021): 281–90. http://dx.doi.org/10.1590/1809-4392202004692.
Abstract (sommario):
ABSTRACT With the expansion of livestock in the Amazon region, a high percentage of pasture areas are degraded and unproductive. Novel strategies are needed, including the use of native tree species, to simultaneously achieve economic and ecosystem benefits. This study aimed at assessing the effects of five multipurpose native tree species on soil fertility and forage quality of Urochloa brizantha pastures in the southern Amazon. Soil and forage samples were collected under the crown and adjacent to 25 isolated trees belonging to five species during a dry and a rainy season. The presence of native trees positively affected the level of potassium, calcium and manganese in the soil, as well as the mineral matter and crude protein of the forage, especially in the dry season, suggesting a protective effect against the seasonal drought. The tree species had variable effects on soil fertility and forage quality. Soil under Apeiba tibourbou had higher potassium levels, while the forage under Handroanthus serratifolius had higher protein and fiber content. Our results indicate that it is important to diversify silvopastoral systems in the Amazon through the use of native tree species, contributing to the design of novel silvopastoral strategies in the region. Common multipurpose tree species with widespread natural distribution could be used as a complementary aspect of pasture management to provide a protective effect against drought, contribute to enhanced nutrient cycling and even increase forage quality.
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Janda, Milan, e Martina Konečná. "Canopy assemblages of ants in a New Guinea rain forest". Journal of Tropical Ecology 27, n. 1 (17 dicembre 2010): 83–91. http://dx.doi.org/10.1017/s0266467410000623.
Abstract (sommario):
Abstract:The ant assemblages in two common tree species in primary lowland forest of New Guinea were explored using direct canopy access and tuna bait traps. The 19 trees investigated were occupied by 21 ant species of which 18 were canopy inhabitants. On average only 3.6 ant species per tree and 3 species per bait were found. Height of bait position was positively related to ant species richness, with the upper parts of the canopy being occupied by the highest number of species. On the other hand, tree species and study site did not have any effect on ant species richness nor on structure of the ant assemblages. Ant species appeared to be distributed randomly and we did not detect any effect of distance on similarity of ant assemblage occurring on the trees. The dominant species (Crematogaster polita) had certain negative effects on the presence of some species at food sources co-occurring at the same tree, but it did co-occur with the other ants to some extent as well. The majority of species found in the canopy were generalist omnivores (depending mainly on trophobionts or plant exudates).
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Monegi, P., N. R. Mkhize, T. J. Tjelele, D. Ward e Z. Tsvuura. "The impact of tree removal on standing grass biomass, seedling establishment and growth of woody species". Rangeland Journal 44, n. 1 (6 aprile 2022): 25–32. http://dx.doi.org/10.1071/rj21003.
Abstract (sommario):
The removal of trees in rangelands can create gaps and lead to increased grass production that could suppress subsequent tree seedling establishment and growth. However, gaps can also enhance the growth of remaining trees. We conducted a field experiment at two savanna sites with different soil texture and woody species. We used 24 plots at each site to determine the effect of tree-removal intensities (0%, 10%, 20%, 50%, 75% and 100%) on grass production, tree-seedling establishment and growth, and growth of the remaining large trees. Site 1 was on previously cultivated severely-eroded clay-dominated soils, encroached by a monospecific stand of Vachellia tortilis. Site 2 had never been cultivated, and was on sandy soils with several woody species. At Site 1, 75 and 100% tree removal significantly reduced standing grass biomass towards the end of the first growing season, with no differences towards the end of the second season. At Site 2, tree removal significantly increased standing grass biomass. There was no significant effect of tree removal on tree seedling establishment at Site 1, but at Site 2 tree removal had a significantly negative effect on overall tree seedling establishment. At both sites, there were no significant differences in tree seedling growth. Moderate (50%) to high (75%) removal of trees had a positive effect on the growth of remaining large trees at both study sites. We found that tree seedling establishment could be affected by the level of grass biomass following tree removal, but other factors including soil erosion are also important considerations. Reduced tree competition facilitates growth of remaining large trees. An implication of these findings is that, regardless of the substantial costs of woody plant control, the recovery of key ecosystem services such as an increased forage production may not be realised. However, we recognise that this may be system-specific.
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Rola, Kaja, Vítězslav Plášek, Katarzyna Rożek e Szymon Zubek. "Effect of tree species identity and related habitat parameters on understorey bryophytes – interrelationships between bryophyte, soil and tree factors in a 50-year-old experimental forest". Plant and Soil 466, n. 1-2 (16 luglio 2021): 613–30. http://dx.doi.org/10.1007/s11104-021-05074-w.
Abstract (sommario):
Abstract Aim Overstorey tree species influence both soil properties and microclimate conditions in the forest floor, which in turn can induce changes in ground bryophyte communities. The aim of the study was to investigate the effect of tree species identity and the most important habitat factors influencing understorey bryophytes. Methods We assessed the effect of 14 tree species and related habitat parameters, including soil parameters, vascular plant presence and light intensity on bryophytes in monospecific plots covered by nearly fifty-year-old trees in the Siemianice Experimental Forest (Poland). Results The canopy tree species determined bryophyte species richness and cover. The strongest differences were observed between plots with deciduous and coniferous trees. Soils with a more acidic pH and lower content of macronutrients supported larger bryophyte coverage. We also found a positive correlations between vascular plants and availability of light as well as bryophyte species richness. Conclusion Tree species identity and differences in habitat conditions in the forest floor lead to changes of ground bryophyte richness, cover and species composition. Consequently, the changes in the dominant tree species in the stand may result in significant repercussions on ground bryophyte communities. We indicated that the introduction of alien tree species, i.e. Quercus rubra, has an adverse effect on bryophyte communities and suggested that the selection of tree species that contribute to the community consistent with the potential natural vegetation is highly beneficial for maintaining ground bryophyte biodiversity.
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Shekanino, Anette, Avaleen Agustin, Annette Aladefa, Jason Amezquita, Demetri Gonzalez, Emily Heldenbrand, Alyssa Hernandez et al. "Differential Stomatal Responses to Surface Permeability by Sympatric Urban Tree Species Advance Novel Mitigation Strategy for Urban Heat Islands". Sustainability 15, n. 15 (3 agosto 2023): 11942. http://dx.doi.org/10.3390/su151511942.
Abstract (sommario):
As urbanization draws more people to metropolitan areas, a steadfast increase in impervious surfaces ultimately contributes to a pronounced urban heat island effect. While city greening strategies to mitigate urban thermal effects often tout street-tree cover expansion, many plant species are susceptible to heat stress, limiting survivorship, primary productivity, and ecosystem services. Our research objective was to characterize how urban imperviousness impacted the photosynthetic traits of four sympatric tree species in Old Town La Verne, California. We found that while Camphor trees (Camphora officinarum) and Carrotwood trees (Cupaniopsis anacardioides) did not differ significantly in photosynthetic traits at sites with impervious and pervious surfaces, both Coast Live Oak trees (Quercus agrifolia) and Olive trees (Olea europaea) showed significant differences in leaf stomatal length and density. Our findings suggest that the photosynthetic traits of some exotic tree species may be less susceptible to surface permeability than either native or floristically indigenous tree species. We propose that urban greening initiatives adopt a temporal strategy for mitigating urban heat island effects, starting with an urban canopy composed of exotic trees more resilient to impervious surfaces and later transitioning to a recombinant canopy ecology of floristically relevant tree species suited for the soil permeability native to southern California.
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Kambach, Stephan, Christopher Sadlowski, Derek Peršoh, Marco Alexandre Guerreiro, Harald Auge, Oliver Röhl e Helge Bruelheide. "Foliar Fungal Endophytes in a Tree Diversity Experiment Are Driven by the Identity but Not the Diversity of Tree Species". Life 11, n. 10 (13 ottobre 2021): 1081. http://dx.doi.org/10.3390/life11101081.
Abstract (sommario):
Symbiotic foliar fungal endophytes can have beneficial effects on host trees and might alleviate climate-induced stressors. Whether and how the community of foliar endophytes is dependent on the tree neighborhood is still under debate with contradicting results from different tree diversity experiments. Here, we present our finding regarding the effect of the tree neighborhood from the temperate, densely planted and 12-years-old Kreinitz tree diversity experiment. We used linear models, redundancy analysis, Procrustes analysis and Holm-corrected multiple t-tests to quantify the effects of the plot-level tree neighborhood on the diversity and composition of foliar fungal endophytes in Fagus sylvatica, Quercus petraea and Picea abies. Against our expectations, we did not find an effect of tree diversity on endophyte diversity. Endophyte composition, however, was driven by the identity of the host species. Thirteen endophytes where overabundant in tree species mixtures, which might indicate frequent spillover or positive interactions between foliar endophytes. The independence of the diversity of endophytes from the diversity of tree species might be attributed to the small plot size and the high density of tree individuals. However, the mechanistic causes for these cryptic relationships still remain to be uncovered.
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Chen, Ya-Jun, Frans Bongers, Kun-Fang Cao e Zhi-quan Cai. "Above- and below-ground competition in high and low irradiance: tree seedling responses to a competing liana Byttneria grandifolia". Journal of Tropical Ecology 24, n. 05 (settembre 2008): 517–24. http://dx.doi.org/10.1017/s0266467408005233.
Abstract (sommario):
Abstract:In tropical forests, trees compete not only with other trees, but also with lianas, which may limit tree growth and regeneration. Liana effects may depend on the availability of above- and below-ground resources and differ between tree species. We conducted a shade house experiment to test the effect of light (4% and 35% full sun, using neutral-density screen) on the competitive interactions between seedlings of one liana (Byttneria grandifolia) and three tree species (two shade-tolerant trees,Litsea dilleniifoliaandPometia tomentosa, and one light-demanding tree,Bauhinia variegata) and to evaluate the contribution of both above- and below-ground competition. Trees were grown in four competition treatments with the liana: no competition, root competition, shoot competition and root and shoot competition. Light strongly affected leaf photosynthetic capacity (light-saturated photosynthetic rate,Pn), growth and most morphological traits of the tree species. Liana-induced competition resulted in reducedPn, total leaf areas and relative growth rates (RGR) of the three tree species. The relative importance of above- and below-ground competition differed between the two light levels. In low light, RGR of the three tree species was reduced more strongly by shoot competition (23.1–28.7% reduction) than by root competition (5.3–26.4%). In high light, in contrast, root competition rather than shoot competition greatly reduced RGR. Liana competition affected most morphological traits (except for specific leaf area and leaf area ratio ofLitseaandPometia), and differentially altered patterns of biomass allocation in the tree seedlings. These findings suggest that competition from liana seedlings can greatly suppress growth in tree seedlings of both light-demanding and shade-tolerant species and those effects differ with competition type (below- and above-ground) and with irradiance.
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LIŠKA, Jiří, e Tomáš HERBEN. "Long-term changes of epiphytic lichen species composition over landscape gradients: an 18 year time series". Lichenologist 40, n. 05 (26 agosto 2008): 437–48. http://dx.doi.org/10.1017/s0024282908006610.
Abstract (sommario):
Abstract:The study aimed to determine how the response of the epiphytic lichen vegetation to sulphur air pollution is affected by interaction with other factors (distance from pollution sources, habitat, altitude, initial eutrophication of the tree bark). It was based on a series of four successive recordings taken over a period of 18 years with increasing pollution levels and on the same set of 139 solitary trees. Relationships between habitat variables and lichen community composition are assessed using canonical correspondence analysis. The data set comprised 69 lichen species. Ordination of initial species composition on trees revealed two major gradients: eutrophication and acidity.The species composition significantly changed with time, with a general decrease of the total number of lichen species per tree. In general, species sensitive to air pollution decreased, while tolerant species increased in number. Change over time differed depending on the position of the tree within the landscape (relative to one major source of pollution, the town of Tábor, whereas the distance to the other source, Sezimovo Ústí, was not significant) and on the initial species composition found on the tree. Trees under the effect of eutrophication changed their species composition less, indicating that the effect of eutrophication (mainly increased bark pH) may ameliorate the effects of air pollution; a local effect of eutrophication also seems to play an important role. Distance to pollution sources had only a small impact on the rate of change and perhaps other local conditions (sheltered or humid position, altitude) play a role in this interaction. There was a decrease of the overall heterogeneity of the data set over time. This means that the gradients in species composition attributable to these variables became less important over time. Therefore, one of the effects of air pollution is also a general homogenization of the lichen vegetation of the solitary trees.
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Liu, Yao, Haotian You, Xu Tang, Qixu You, Yuanwei Huang e Jianjun Chen. "Study on Individual Tree Segmentation of Different Tree Species Using Different Segmentation Algorithms Based on 3D UAV Data". Forests 14, n. 7 (28 giugno 2023): 1327. http://dx.doi.org/10.3390/f14071327.
Abstract (sommario):
Individual structural parameters of trees, such as forest stand tree height and biomass, serve as the foundation for monitoring of dynamic changes in forest resources. Individual tree structural parameters are closely related to individual tree crown segmentation. Although three-dimensional (3D) data have been successfully used to determine individual tree crown segmentation, this phenomenon is influenced by various factors, such as the (i) source of 3D data, (ii) the segmentation algorithm, and (iii) the tree species. To further quantify the effect of various factors on individual tree crown segmentation, light detection and ranging (LiDAR) data and image-derived points were obtained by unmanned aerial vehicles (UAVs). Three different segmentation algorithms (PointNet++, Li2012, and layer-stacking segmentation (LSS)) were used to segment individual tree crowns for four different tree species. The results show that for two 3D data, the crown segmentation accuracy of LiDAR data was generally better than that obtained using image-derived 3D data, with a maximum difference of 0.13 in F values. For the three segmentation algorithms, the individual tree crown segmentation accuracy of the PointNet++ algorithm was the best, with an F value of 0.91, whereas the result of the LSS algorithm yields the worst result, with an F value of 0.86. Among the four tested tree species, the individual tree crown segmentation of Liriodendron chinense was the best, followed by Magnolia grandiflora and Osmanthus fragrans, whereas the individual tree crown segmentation of Ficus microcarpa was the worst. Similar crown segmentation of individual Liriodendron chinense and Magnolia grandiflora trees was observed based on LiDAR data and image-derived 3D data. The crown segmentation of individual Osmanthus fragrans and Ficus microcarpa trees was superior according to LiDAR data to that determined according to image-derived 3D data. These results demonstrate that the source of 3D data, the segmentation algorithm, and the tree species all have an impact on the crown segmentation of individual trees. The effect of the tree species is the greatest, followed by the segmentation algorithm, and the effect of the 3D data source. Consequently, in future research on individual tree crown segmentation, 3D data acquisition methods should be selected based on the tree species, and deep learning segmentation algorithms should be adopted to improve the crown segmentation of individual trees.
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Ngetich, Samuel Kiplangat. "Effect of Tapping on Gum and Incense Yield of Selected Trees Species in Elwaye and Dhas Districts, Borana Zone, Southern Oromia". East African Journal of Forestry and Agroforestry 6, n. 1 (27 luglio 2023): 211–26. http://dx.doi.org/10.37284/eajfa.6.1.1334.
Abstract (sommario):
Ethiopia is one of the Gum and Resin producing countries with a large potential. Borana pastoralists particularly utilised these resources as a source of revenue. The majority of Ethiopia’s gum-resin products are collected from natural oozing. In southern Ethiopia, improved tapping mechanisms are uncommon. This study was conducted to determine the effect of different tapping machines and tapping at different tree diameter classes on the gum and incense yields of selected tree species. Commiphora corrugata, Boswellia microphylla, and Boswellia neglecta tree species were selected for their potential existence and economic importance. A factorial experiment was arranged in a randomised complete block design (RCBD) in which three types of tapping materials including natural oozing and three levels of tree size (diameter classes) were used. Accordingly, materials (Panga, Axe, Sonki, and control) were applied at diameters of (5-8 cm, 8.1-11 cm and >11 cm) for a tree height below DBH (at < 130 cm) and above DBH (at >130 cm) on selected tree species while natural oozing was remained untapped and used as controls. Accordingly, the highest mean yield was recorded for trees tapped by axe (5.99 g/tree), followed by Sonki (5.01 g/tree) and bigger diameter class >11 cm (7.10 g/tree) for Commiphora corrugata. The highest mean yield was also obtained for trees tapped by axe (10.76 g/tree) in the first year and (43.71 g/tree) in the second year and bigger diameter class >11 cm (15.16 g/tree) in the first year and (47.81 g/tree) in the second year for Boswellia microphylla. Moreover, the highest mean yield was recorded for naturally oozing trees (6.16 g/tree) and bigger diameter class >11 cm (6.33 g/tree) for Boswellia neglecta. Tapped trees generally provided significantly higher yields than untapped or control trees, and frankincense yield increased with increasing tree size
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S. O., Ihinmikaiye. "THREAT OF CHARCOAL PROCESSING TO TREE SPECIES DIVERSITY IN OTEMEWO COMMUNITY, OKPE, DELTA STATE, NIGERIA". International Journal of Engineering Applied Sciences and Technology 8, n. 1 (1 maggio 2023): 1–8. http://dx.doi.org/10.33564/ijeast.2023.v08i01.001.
Abstract (sommario):
The status of tree species used for charcoal processing and its effect on tree diversity in Otemewo community, Okpe Delta State were assessed. Semistructured questionnaire guide and random sampling technique were used to collect data on the trees species. Besides five points likert rating scale on species preference for charcoal, and paired t-test was used to determine the implication of tree species preference for charcoal production on tree diversity. A major charcoal processing site was selected for the study. Also samplings were done in two randomly selected sample plots. Twenty eight (28) tree species belonging to 13 different families were cited as trees preferred for charcoal processing. Meanwhile, only ten (10) species: B. cogolensis, E. cylindricum, I. gabonensis, K. senegalensis, L. alata, L. lanceolata, P. africana, P. macrophylla, T. orientalisand U. guineensis of the twenty eight (28) trees recorded as charcoal-producing species existed in the two sample plots, and were comparatively rare. Diversity indices reveal that one of the two randomly selected plots was richer in tree species than the other. Consequently, it was observed that high rate of deforestation and unsustainable collection pattern of trees for charcoal threatens forest ecosystem and negatively affected the diversity of tree species in the area. Therefore, strategies that would ensure tree species management and by extension the entire forest ecosystem of the area were suggested.
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Rezapour, Azadeh, Mohammadreza Labbafi e Tõnu Oja. "The impact of soil warming on fine root trait responses of trees, deciduous vs. coniferous: a meta-analysis". Forestry Studies 77, n. 1 (1 dicembre 2022): 67–75. http://dx.doi.org/10.2478/fsmu-2022-0013.
Abstract (sommario):
Abstract We compiled data from 149 paired observations from 43 publications and performed a meta-analysis to evaluate the variability of trees’ fine root trait responses under various global soil warming experiments. The impacts of warming magnitude, soil depth, and different tree species (deciduous vs. coniferous), on the responses of fine root biomass (FRB), and fine root morphology were assessed in this study. Our results confirmed that soil warming increased FRB while having no significant effect on fine root morphological traits, such as specific root length (SRL), specific root area (SRA), and diameter (D). The effect of warming on FRB decreased significantly at higher warming magnitude. The effect of tree species was also evident in the response of FRB to soil warming magnitude. Furthermore, warming effects on SRA and D increased in deeper soil horizons. The present meta-analysis provides an improved understanding of trees’ fine roots and the tree species-specific adaptive strategy under future soil warming episodes. Our results suggest that trees will resist the altering soil warming conditions by modifications more in fine root biomass allocation rather than morphological adjustments.
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Madureira, Marcelo Silva, Tathiana Guerra Sobrinho e José Henrique Schoereder. "The Influence of Extrafloral Nectaries on Arboreal Ant Species Richness in Tree Communities". Sociobiology 65, n. 2 (9 luglio 2018): 162. http://dx.doi.org/10.13102/sociobiology.v65i2.1939.
Abstract (sommario):
Studies investigating the role of resource availability in the species richness patterns can elucidate ecological processes and contribute to conservation strategies. In this study, we test two hypotheses: i) arboreal ant species richness increases with abundance of extrafloral nectaries-bearing trees; and ii) arboreal ant species richness increases with the diversity of extrafloral nectaries-bearing trees. We used data of ant sampling and tree inventories from 30 plots of Brazilian Cerrado. Arboreal ant species richness was positively influenced by the proportional abundance of extrafloral nectaries-bearing trees, total tree density and total tree diversity. There was no effect of species richness of extrafloral nectaries-bearing trees. Coefficient of determination of proportional abundance of extrafloral nectaries-bearing trees was larger when compared to coefficient obtained using tree density as explanatory variable. These results suggest that variation in arboreal ant species richness is better explained by extrafloral nectaries-bearing tree abundance than total tree density. Generalist foraging behavior of sampled ant species may explain their association with proportional abundance of extrafloral nectariesbearing trees and their non-significant relation with proportional richness of extrafloral nectaries-bearing tree species. Extrafloral nectaries-bearing trees abundance may be a specific estimate of the amount of food resource available in plots. Thus, this is a more specific way to quantify which resources may explain variation of the arboreal ant species richness in tree communities. We hope these results will be helpful to understanding the local variation in ant species richness and as criteria to biodiversity conservation.
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Tatsumi, Shinichi, e Toshiaki Owari. "Modeling the effects of individual-tree size, distance, and species on understory vegetation based on neighborhood analysis". Canadian Journal of Forest Research 43, n. 11 (novembre 2013): 1006–14. http://dx.doi.org/10.1139/cjfr-2013-0111.
Abstract (sommario):
Quantifying how understory vegetation responds to individual neighboring trees is critical to understanding forest dynamics. To do so, we used a spatial neighborhood approach to quantify the competitive effect of individual trees on the density and height of dwarf bamboo (Sasa senanensis (Franch. et Savat.) Rehder) in a mixed conifer–broadleaf forest on the island of Hokkaido, northern Japan. Using hierarchical Bayesian models, we analyzed how the effect of neighboring trees varies with stem size, distance to the dwarf bamboo, and tree species. The effect of neighbors peaked when the tree reached a medium size (33.0–45.0 cm in diameter at breast height) and decreased for larger trees. The effect of neighbors decreased with increasing distance to the dwarf bamboo. The slope of the decrease was gentler for larger trees. Conifers exerted an average of 7.2 times the effect of broadleaved trees. Species with higher shade tolerance exerted larger effects. Species with late leaf flush and early defoliation tended to exert smaller effects. Our results provide evidence that neighborhood analysis is an effective approach for quantifying the effects of individual trees on understory vegetation and represents a critical step toward understanding how fine-scale interactions between understory vegetation and trees influence overall forest dynamics.
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Wu, Shaowei, Xiaojie Yao, Yinqi Qu e Yawen Chen. "Ecological Benefits and Plant Landscape Creation in Urban Parks: A Study of Nanhu Park, Hefei, China". Sustainability 15, n. 24 (5 dicembre 2023): 16553. http://dx.doi.org/10.3390/su152416553.
Abstract (sommario):
Plant landscape creation in urban parks is an important aspect of urban ecological construction under the goal of “carbon neutrality”. In this study, the plant community of Nanhu Park in Hefei City was considered the research subject, and its tree species’ composition and diameter at breast height (DBH) were analyzed. The ecological benefits of the park’s green space were evaluated using the i-tree Eco model, and the carbon sequestration, runoff retention, air pollution removal, and oxygen production benefits were quantified as economic values and combined with the landscape effect evaluation method. The results show that Nanhu Park is rich in tree species types, with 5871 trees of 41 species in 23 families and 32 native species, among which three species of Sapindus mukorossi, Eucommia ulmoides, and Triadica sebifera accounted for 43.7% of the total number of trees. The dominant tree DBH was intermediate (7.6–15.2 cm). In Nanhu Park, the economic benefits were ordered as follows: carbon sequestration > runoff retention > air pollution removal > oxygen production benefits. The dominant tree species strongly contributed to the total ecological benefit of urban park green space; the ecological benefit of individual trees was not positively correlated with the number of tree species; native tree species had better ecological and landscape effects, while plant communities with growth changes and hierarchical depth of landscape were more popular. The analysis of ecological benefits and landscape evaluation of urban park green space provide a theoretical basis for enhancing the plant landscape, thus providing a case reference for promoting the construction of park green space in Hefei.
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Fang, Fuh-Min, Jen-Chieh Chang, Yi-Chao Li, Cheng-Yang Chung e Ming-Hsun Chan. "Shelter Effect of Pedestrian Wind behind Row Trees in a Line Arrangement". Forests 13, n. 3 (27 febbraio 2022): 392. http://dx.doi.org/10.3390/f13030392.
Abstract (sommario):
Flow past a single-line arrangement of evenly-spaced row trees, in an open territory, was numerically simulated under the action of a boundary-layer type of oncoming flow, with a strength of “strong breeze”, based on the Beaufort scale. By selecting Koelreuteria henryi as the demonstrated tree species, the spatial wind speed variations behind row trees at the pedestrian level, at various tree heights and tree spaces, were analyzed to investigate the corresponding downstream shelter effects from a systematic basis. Based on the results of the analyses, the tendency of stream-wise wind speed variations behind the row trees was presented so as to provide additional insights into row-tree planning for protection against ground wind. Moreover, in other cases of row trees with similar crown shapes and properties, resulting flow fields for various tree heights and tree spaces can provide referable quantitative information, which can be readily used to conduct tentative shelter effect assessments and pedestrian comfort evaluations in a preliminary planning stage.
20
Gudiel, A. Andrea, Shane C. Nieves, Kim E. Reuter e Brent J. Sewall. "The effect of anthropogenic disturbance on non-native plant species in Madagascar". Journal of Tropical Ecology 32, n. 6 (4 ottobre 2016): 543–54. http://dx.doi.org/10.1017/s0266467416000481.
Abstract (sommario):
Abstract:Non-native species impact tropical ecosystems, but the role of different anthropogenic disturbances on the success of non-natives remains unclear, especially in island tropical forests. We sought to understand the influence of anthropogenic habitat degradation and disturbance on non-native plant species in Madagascar. Specifically, we evaluated how densities of non-native species of woody shrub (Lantana camara), climber (Mucuna pruriens) and tree (Mangifera indica, Albizia lebbeck, Tamarindus indica) varied with forest habitat degradation and by disturbance type. We surveyed 60400 m2, recording 482 instances of disturbance and 903 non-native plants in and around the Ankarana National Park. Non-native plant densities were higher in degraded than primary forest. Within degraded forest, densities of non-native trees increased with disturbance. Tree densities correlated with extent of tree damage only in Tamarindus indica, never correlated with extent of tree removal, and always correlated with proximity to roads and trails. Our results suggest roads and trails have relatively greater importance in facilitating the success of non-native tree species than structural changes to habitat. In contrast, densities of Lantana camara and Tamarindus indica did not correlate with any measured type of disturbance; other unmeasured or historical factors may be more important drivers of these smaller, faster-reproducing species.
21
Clay, Keith, Angela L. Shelton e Chuck Winkle. "Effects of oviposition by periodical cicadas on tree growth". Canadian Journal of Forest Research 39, n. 9 (settembre 2009): 1688–97. http://dx.doi.org/10.1139/x09-090.
Abstract (sommario):
Periodical cicadas ( Magicicada spp.) occur at very high densities and synchronously emerge from underground every 13 or 17 years. During the emergence, adults lay eggs in tree branches, causing significant damage; however, the long-term impact of this damage is unknown. We conducted two large-scale field studies during the 2004 emergence of one brood (Brood X) to measure the growth of trees in relation to oviposition damage by periodical cicadas. In the first experiment, we netted areas to exclude cicadas from plots in 15 early successional forests and then measured trunk circumference for 3 years on more than 4000 trees of 52 species. In this experiment, oviposition had no detectable effect on the growth rates of trees. In the second study, we measured oviposition on 12 common tree species across six sites. We then measured the annual growth rings of these trees for 3 years after the emergence. In this experiment, oviposition was correlated with a slightly reduced growth in the emergence year and following year when the data were analyzed together, but when tree species were examined individually there were no clear effects of oviposition on tree growth. These data suggest cicada oviposition has little effect on the radial growth of trees, particularly in comparison to other factors.
22
Yusof, Nor Suhaida, Nur Huzeima Mohd Hussain e Noradila Rusli. "THE RELATIONSHIP OF HERITAGE TREES IN URBAN HEAT ISLAND MITIGATION EFFECT AT TAIPING, PERAK, MALAYSIA". Malaysian Journal of Sustainable Environment 3, n. 2 (31 dicembre 2017): 157. http://dx.doi.org/10.24191/myse.v3i2.5601.
Abstract (sommario):
Every tree species provide different cooling effect depending on their tree characteristics. Evergreen species such as heritage trees are significant in reducing the surface temperature. The aim of this paper is to determine the relationship of heritage trees in mitigating urban heat island at Taiping Old Town. The research had been conducted through Landsat 8 OLI and field data collection. This research integrated the Geographic Information System (GIS) and remote sensing in data processing and analysis. The results show the low significant relationship of tree characteristics and Land Surface Temperature (LST) with (R²=0.17) which indicate that external factors may also influence the changes in temperature.
23
Vadeboncoeur, Matthew A., Katie A. Jennings, Andrew P. Ouimette e Heidi Asbjornsen. "Correcting tree-ring δ13C time series for tree-size effects in eight temperate tree species". Tree Physiology 40, n. 3 (24 gennaio 2020): 333–49. http://dx.doi.org/10.1093/treephys/tpz138.
Abstract (sommario):
Abstract Stable carbon isotope ratios (δ13C) in tree rings have been widely used to study changes in intrinsic water-use efficiency (iWUE), sometimes with limited consideration of how C-isotope discrimination is affected by tree height and canopy position. Our goals were to quantify the relationships between tree size or tree microenvironment and wood δ13C for eight functionally diverse temperate tree species in northern New England and to better understand the physical and physiological mechanisms underlying these differences. We collected short increment cores in closed-canopy stands and analyzed δ13C in the most recent 5 years of growth. We also sampled saplings in both shaded and sun-exposed environments. In closed-canopy stands, we found strong tree-size effects on δ13C, with 3.7–7.2‰ of difference explained by linear regression vs height (0.11–0.28‰ m−1), which in some cases is substantially stronger than the effect reported in previous studies. However, open-grown saplings were often isotopically more similar to large codominant trees than to shade-grown saplings, indicating that light exposure contributes more to the physiological and isotopic differences between small and large trees than does height. We found that in closed-canopy forests, δ13C correlations with diameter at breast height were nonlinear but also strong, allowing a straightforward procedure to correct tree- or stand-scale δ13C-based iWUE chronologies for changing tree size. We demonstrate how to use such data to correct and interpret multi-decadal composite isotope chronologies in both shade-regenerated and open-grown tree cohorts, and we highlight the importance of understanding site history when interpreting δ13C time series.
24
CARSTEN, L. D., F. A. JUOLA, T. D. MALE e S. CHERRY. "Host associations of lianas in a south-east Queensland rain forest". Journal of Tropical Ecology 18, n. 1 (gennaio 2002): 107–20. http://dx.doi.org/10.1017/s0266467402002067.
Abstract (sommario):
Lianas are abundant in tropical forests around the world, yet little is known about their ecology. In this study we report the results of a survey of ten common liana species on 27 host tree species in Cooloola National Park, Queensland, Australia. We found significant associations between some liana and tree species. Our results indicate that host tree diameter was important in explaining liana presence or absence. Host tree fruit type was correlated with the presence or absence of different liana types. Tendrillar and root-climbing lianas tended to occur most often on mid-sized, fleshy-fruited trees, and on smaller, non-fleshy-fruited trees. The presence of stem twining lianas tended to decrease with increasing tree diameter for both fleshy- and non-fleshy-fruited trees, although this effect was more pronounced for fleshy-fruited trees. In general, lianas were most prevalent on trees possessing intermediate levels of bark roughness and flakiness. Although we established associative patterns between liana species and these host characteristics, the model suggested that other unidentified variables may also be important in determining presence or absence of liana species.
25
V Podrázský, V., e J. Remeš. "Effect of forest tree species on the humus form state at lower altitudes ". Journal of Forest Science 51, No. 2 (10 gennaio 2012): 60–66. http://dx.doi.org/10.17221/4544-jfs.
Abstract (sommario):
The paper documents the effects of forest stands of different species composition on the humus form state and soil profile chemistry. It compares the situation in mixed broadleaved (ash, oak, hornbeam), basswood and spruce stands. Spruce demonstrates the site degradation effects: raw humus accumulation, soil acidification, negative effects on nutrient dynamics. Both broadleaved stands were similar as for site effects, lower litter accumulation, more rapid organic matter mineralization and more rapid nutrient cycling and intense uptake were documented in the basswood stand.
26
He, Chong, Dan Liang e Peng Zhang. "Asymmetric Distribution of Gene Trees Can Arise under Purifying Selection If Differences in Population Size Exist". Molecular Biology and Evolution 37, n. 3 (22 ottobre 2019): 881–92. http://dx.doi.org/10.1093/molbev/msz232.
Abstract (sommario):
Abstract Incomplete lineage sorting (ILS) is an important factor that causes gene tree discordance. For gene trees of three species, under neutrality, random mating, and the absence of interspecific gene flow, ILS creates a symmetric distribution of gene trees: the gene tree that accords with the species tree has the highest frequency, and the two discordant trees are equally frequent. If the neutral condition is violated, the impact of ILS may change, altering the gene tree distribution. Here, we show that under purifying selection, even assuming that the fitness effect of mutations is constant throughout the species tree, if differences in population size exist among species, asymmetric distributions of gene trees will arise, which is different from the expectation under neutrality. In extremes, one of the discordant trees rather than the concordant tree becomes the most frequent gene tree. In addition, we found that in a real case, the position of Scandentia relative to Primate and Glires, the symmetry in the gene tree distribution can be influenced by the strength of purifying selection. In current phylogenetic inference, the impact of purifying selection on the gene tree distribution is rarely considered by researchers. This study highlights the necessity of considering this impact.
27
Rawana, Agus Prijono, Teddy Suparyanto, Digdo Sudigyo e Bens Pardamean. "Light intensity effect on number of seedlings and growth of Gyrinops versteegii". IOP Conference Series: Earth and Environmental Science 1183, n. 1 (1 maggio 2023): 012046. http://dx.doi.org/10.1088/1755-1315/1183/1/012046.
Abstract (sommario):
Abstract Due to the depletion of its natural population, the Gyrinops versteegii species, one of the species producing agarwood, has been domesticated in Indonesia, particularly in Sragen Central Java. As a result, it was designated as a vulnerable species in both CITES Appendix II and the IUCN Red List Ver23. The research objective is to determine the effect of the light intensity on the number of seedlings, tree density, height, and diameter of the G.versteegii tree growth. The study was conducted from February to October 2018 at a domesticated agarwood community forest in Sragen, Central Java. A systematic plot method, a random start, was applied to this research with 28 nested plots, 1x1 m2 for seedlings and 10x10 m2 for the trees. The data were analyzed using both hierarchical clustering and correlation analysis. The relative light intensity of 2,82% led to an enormous number of seedlings and tree diameter, while the relative light intensity of 0.31% resulted in the highest tree density. The number of seedlings and tree diameter was strongly correlated with the relative light intensity. In contrast, there is an inverse relationship between tree density and relative light intensity.
28
Balraju, Wagmare, e S. K. Tripathi. "Potential Trees Species of North-East India for Dendroclimatological Studies". Environment and Ecology 41, n. 3B (agosto 2023): 1821–31. http://dx.doi.org/10.60151/envec/vldz2030.
Abstract (sommario):
Many tropical trees show distinct annual ring formation as in temperate conifers, and the growth of these annual rings is used as bio-indicators of environmental changes. Dendroclimatology is the science dealing with the reconstruction of a history of past climate through dendrochronological (tree ring) analysis and assessing the effect of climatic change on tree growth. Trees are living natural archives and their growth is largely impacted by various climatic and non-climatic events occurring in the surrounding environments. In Northeast India, several conifers and broad-leaf tree species such as Abies densa, Larix griffithii, Pinus merkusii, Pinus kesiya, Pinus wallichiana, Quercus serrata, Toona ciliata and Tectona grandis have been used for tree ring-based studies. Dendrochronological studies mainly focused on the reconstruction of climate history, climate-tree growth relationship, river flow history reconstruction, inter-annual density fluctuation, and for development of climate proxies. Among these, the oldest tree ring chronology of Abies densa of 490 years (1504 to 1994) was reported from Yumthang of Sikkim. Whereas the youngest chronology of Toona ciliata of 35 years (1984 to 2018) was from Chandel district of Manipur. The knowledge derived from the detailed study of these species will help forest managers and conservationists to manage the forest in a changing environment. This paper presented dendrochronological information of different trees of northeast India based on the published literature and their possible impact on climate reconstruction through dendroclimatology. However, further potential tree species forming tree rings need to be worked out for possible climate mitigation measures of tropical trees in northeast India.
29
Canham, Charles D., Philip T. LePage e K. Dave Coates. "A neighborhood analysis of canopy tree competition: effects of shading versus crowding". Canadian Journal of Forest Research 34, n. 4 (1 aprile 2004): 778–87. http://dx.doi.org/10.1139/x03-232.
Abstract (sommario):
We have developed extensions of traditional distance-dependent, spatial competition analyses that estimate the magnitude of the competitive effects of neighboring trees on target tree growth as a function of the species, size, and distance to neighboring trees. Our analyses also estimate inter- and intra-specific competition coefficients and explicitly partition the competitive effects of neighbors into the effects of shading versus crowding. We tested the method using data from forests of northern, interior British Columbia dominated by western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western redcedar (Thuja plicata Donn ex D. Don). For both species, the most parsimonious regression models included terms for the effects of tree size, crowding, and shading and separate competitive effects of four different groups of competing species. The models explained 33%59% of the variation in radial growth of the two species. For both species, growth declined more steeply as a function of crowding than shading. There was striking asymmetry in the strength of interspecific competition between hemlock and redcedar, with crowding by hemlock having a strong per capita effect on redcedar, while crowding by redcedar had relatively little effect on the radial growth of hemlock.
30
Volkova, Irina, Kseniia Pitulko, Anzhelika Sergeeva e Saida Pshidatok. "Development of Forest Shelterbelts Considering Statistical Forecasts Modelling of Local Weather". Asian Journal of Water, Environment and Pollution 18, n. 1 (25 gennaio 2021): 7–14. http://dx.doi.org/10.3233/ajw210002.
Abstract (sommario):
This work aims to study the effect of high temperatures and phytopathogenic bacteria on different types of trees in the forest shelterbelts. Therefore, in 2018, 17 tree species were studied from 50 sample sites in the Moscow oblast (Russia). Leaf scorching, diseases caused by phytopathogenic bacteria, and heat damage to the crowns were examined in 5224 tree species. Based on the degree of crown damage, the studied tree species were divided into four classes. It was found that the heat damage to tree crowns was identical between the three sampling aspects (correlation coefficient 0.99). The plant species composition must be considered when developing forest shelterbelts. A long-term forecast on structural changes of planted areas is possible, considering the species composition and climatic characteristics of the region. Class 5 includes only chestnut; class 4 includes three species; class 3 is represented by seven species. Class 2, includes six species, and is the most suitable in developing forest plantations. No tree species in class 1 were found (trees with no damage). There is a connection between pathologies and heat injuries in trees from classes 4 to 5 (correlation 0.89).
31
Zhukov, Oleksandr V., Olga M. Kunah, Yuliya Y. Dubinina, Marina P. Fedushko, Vadim I. Kotsun, Yuliya O. Zhukova e Olena V. Potapenko. "Tree canopy affects soil macrofauna spatial patterns on broad- and meso-scale levels in an Eastern European poplar-willow forest in the floodplain of the River Dnipro". Folia Oecologica 46, n. 2 (1 dicembre 2019): 101–14. http://dx.doi.org/10.2478/foecol-2019-0013.
Abstract (sommario):
AbstractThis paper tested the hypothesis that the placement of trees in the floodplain ecosystem leads to multiscale spatial structuring and plays an important role in formation of the spatial patterns of the soil macrofauna. The research polygon was laid in an Eastern European poplar-willow forest in the floodplain of the River Dnipro. The litter macrofauna was manually collected from the soil samples. The distances of the sampling locations from the nearest individual of each tree species were applied to obtain a measure of the overstorey spatial structure. The pure effect of tree structured space on the soil animal community was presented by the broad-scale and meso-scale components. The soil animal community demonstrated patterns varying in tree structured space. The tree induced spatial heterogeneity was revealed to effect on the vertical stratification of the soil animal community. The complex nature of the soil animal community variability depending on the distance from trees was depended on the interaction of tree species in their effects on soil animals. The importance of the spatial structures that interact with soil, plants and tree factors in shaping soil macrofauna communities was shown.
32
Linkevičius, Edgaras, e Gerda Junevičiūtė. "Effect of Competition and Climatic Conditions on the Growth of Beech in the Mixed Pine Beech Stand: Lithuanian Case Study". Environmental Sciences Proceedings 3, n. 1 (12 novembre 2020): 49. http://dx.doi.org/10.3390/iecf2020-07961.
Abstract (sommario):
Climate change and warming will potentially have profound effects on forest growth and yield, especially for pure stands in the near future. Thus, increased attention has been paid to mixed stands, e.g., pine and beech mixtures. However, the interaction of tree species growing in mixtures still remains unknown. Thus, the aim of this study was to investigate the impact of the interspecific and intraspecific competition to diameter, height, and crown width of pine and beech trees growing in mixtures, as well as to evaluate the impact of climatic indicators to the beech radial diameter increment. The data was collected in 2017 at the mixed mature pine beech double layer stand, located in the western part of Lithuania. The sample plot of 1.2 hectare was established and tree species, diameter at the breast height, tree height, height-to-crown base, height-to-crown width, and position were measured for all 836 trees. Additionally, a representative sample of radial diameter increments were estimated only for the beech trees by taking out core discs at the height of 1 m when the stand was partially cut. Competition analysis was based on the distance-dependent competition index, which was further based on crown parameters. Climatic effect was evaluated using classification and regression tree (CART) analysis. We found almost no interspecific competition effect to diameter, height, or crown width for both tree species growing in the first layer. However, it had an effect on beeches growing in the second layer. The intraspecific competition effect was important for pine and beech trees, showing a negative effect for both of them. Our results show the possible coexistence of these tree species due to niche differentiation. An analysis of climatic indicators from 1991–2005 revealed that precipitation from February–May of the current vegetation year and mean temperatures from July to September expressed radial diameter increment effects for beech trees. Low temperatures during March and April, as well as high precipitation during January, had a negative effect on beech radial increments. From 2006–2016, the highest effect on radial diameter increments was the mean temperatures from July to September, as well as the precipitation in January of the current year. From 1991–2016, the highest effect on radial diameter increments was the temperature from July to September 1991–2016 and the precipitation in June 1991–2016. Generally, cool temperatures and higher precipitation in June had a positive effect on beech radial increments. Therefore, our results show a sensitivity to high temperatures and droughts during summer amid Lithuanian’s growth conditions.
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Chan, Woei Leong, Yongdong Cui, Siddharth Sunil Jadhav, Boo Cheong Khoo, Heow Pueh Lee, Chi Wan Calvin Lim, Like Gobeawan et al. "Experimental study of wind load on tree using scaled fractal tree model". International Journal of Modern Physics B 34, n. 14n16 (10 aprile 2020): 2040087. http://dx.doi.org/10.1142/s0217979220400871.
Abstract (sommario):
Green urbanism has stimulated more research on the aerodynamics of tree in recent years. The insight gained in studying wind load on trees would mitigate risk of tree falling and enable sustainable landscape planning. However, deciphering the effect of wind on trees is a daunting task because trees come in various species, shapes and sizes. In this study, we aim at conducting wind tunnel tests on various species of trees, including measuring the respective drag coefficient and turbulent flow field using a force balance and particle image velocimetry system. The wind tunnel experiment is conducted using scaled down fractal tree model at 10 and 15 m/s. The 3D-printed tree model is grown based on the data collected on the species-specific tree parameters, such as the height, trunk diameters, crown box dimensions, etc. In this paper, the wind tunnel result of Yellow Flame (Peltophorum pterocarpum) is presented. Results show that the drag coefficient for this inflexible tree model is not sensitive to wind speed. The Reynolds shear stress and turbulence kinetic energy are observed to be the largest at the top and bottom of the crown where the velocity gradients are the highest.
34
Brookhouse, Matthew, e Cris Brack. "The effect of age and sample position on eucalypt tree-ring width series". Canadian Journal of Forest Research 38, n. 5 (maggio 2008): 1144–58. http://dx.doi.org/10.1139/x07-184.
Abstract (sommario):
In this study, we examine within-tree variance in proportionate tree-ring width (prw) and correlation between radii (rwt), samples (rbh), and trees (rbt) in four eucalypt species common throughout eastern Victoria, Australia. In all species and sites studied, rwt and rbh differ significantly between cambial-age and sample-height classes. Differences between rwt and rbh are nonsignificant between tree-age or radial-azimuth classes. Significant differences in prw exist between cambial-age, tree-age, and sample-height classes and between radii on different compass bearings. Whilst differences in rwt and rbh between cambial-age classes appears to be the result of variation in mechanical demands with increasing stem size, stem deformation may account for differences between sample-height classes. Variation in prw appears to be due to stem geometry, stem eccentricities associated with root buttressing, and tree-age dependent variation in the rate of radial growth. No significant differences in rbt exist between sample-height classes. Analysis of the expressed population signal statistic indicates that site-level and species differences are far more significant than sample position on variance within tree-ring width series collected from eucalypts. We discuss the implications of the current work for eucalypt dendroclimatology.
35
Pensa, Margus, Helen Karu, Aarne Luud, Elga Rull e Riina Vaht. "The effect of planted tree species on the development of herbaceous vegetation in a reclaimed opencast". Canadian Journal of Forest Research 38, n. 10 (ottobre 2008): 2674–86. http://dx.doi.org/10.1139/x08-098.
Abstract (sommario):
The establishment of plantations is the most common method of opencast reclamation, but few studies have addressed the influence of planted trees on the recovery of biodiversity in new forest sites. The goal of this study was to determine whether the formation of herbaceous vegetation was dependent on the tree species planted on the spoil of a reclaimed oil shale opencast in northeastern Estonia. From 2002 to 2005, the vegetation in eight different site types (distinguished according to the age and composition of tree layer) was surveyed. The results confirmed that the development of herbaceous vegetation was controlled by the dominant species of tree layer. The highest number of herbaceous species was recorded in naturally developed mixed stands. As compared with other site types, the herb layers of the pioneer stage (the vegetation in recently reclaimed sites) and alder stands were the most different. In the terms of the competitive, stress-tolerant, and ruderal strategy types, alder (Alnus spp.) stands tended to enhance the growth of competitors, whereas stress-tolerant species were more abundant in pine stands. Herbaceous vegetation remained sparse in coniferous stands, whereas broad-leaved trees tended to improve the performance of herbaceous species. Our results concur with the suggestions that planting with different tree species is one prerequisite for the development of diverse herb layer.
36
Nell, Colleen S., Luis Abdala-Roberts, Victor Parra-Tabla e Kailen A. Mooney. "Tropical tree diversity mediates foraging and predatory effects of insectivorous birds". Proceedings of the Royal Society B: Biological Sciences 285, n. 1890 (7 novembre 2018): 20181842. http://dx.doi.org/10.1098/rspb.2018.1842.
Abstract (sommario):
Biodiversity affects the structure of ecological communities, but little is known about the interactive effects of diversity across multiple trophic levels. We used a large-scale forest diversity experiment to investigate the effects of tropical tree species richness on insectivorous birds, and the subsequent indirect effect on predation rates by birds. Diverse plots (four tree species) had higher bird abundance (61%), phylogenetic diversity (61%), and functional diversity (55%) than predicted based on single-species monocultures, which corresponded to higher attack rates on artificial caterpillars (65%). Tree diversity effects on attack rate were driven by complementarity among tree species, with increases in attack rate observed on all tree species in polycultures. Attack rates on artificial caterpillars were higher in plots with higher bird abundance and diversity, but the indirect effect of tree species richness was mediated by bird diversity, providing evidence that diversity can interact across trophic levels with consequences tied to ecosystem services and function.
37
Velho, Nandini, Aparajita Datta e Kavita Isvaran. "Effect of rodents on seed fate of five hornbill-dispersed tree species in a tropical forest in north-east India". Journal of Tropical Ecology 25, n. 5 (settembre 2009): 507–14. http://dx.doi.org/10.1017/s0266467409990083.
Abstract (sommario):
Abstract:Hornbills are important dispersers of a wide range of tree species. Many of these species bear fruits with large, lipid-rich seeds that could attract terrestrial rodents. Rodents have multiple effects on seed fates, many of which remain poorly understood in the Palaeotropics. The role of terrestrial rodents was investigated by tracking seed fate of five hornbill-dispersed tree species in a tropical forest in north-east India. Seeds were marked inside and outside of exclosures below 6–12 parent fruiting trees (undispersed seed rain) and six hornbill nest trees (a post-dispersal site). Rodent visitors and seed removal were monitored using camera traps. Our findings suggest that several rodent species, especially two species of porcupine were major on-site seed predators. Scatter-hoarding was rare (1.4%). Seeds at hornbill nest trees had lower survival compared with parent fruiting trees, indicating that clumped dispersal by hornbills may not necessarily improve seed survival. Seed survival in the presence and absence of rodents varied with tree species. Some species (e.g. Polyalthia simiarum) showed no difference, others (e.g. Dysoxylum binectariferum) experienced up to a 64% decrease in survival in the presence of rodents. The differing magnitude of seed predation by rodents can have significant consequences at the seed establishment stage.
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Chaudhary K. H., J. R. Jat, R. V. Joshi e Patel, D. J. "Effect of Different Multipurpose Tree Species on Physico-chemical Properties of Loamy Sand Soil Under Rainfed Conditions". International Journal of Plant & Soil Science 36, n. 6 (28 maggio 2024): 910–17. http://dx.doi.org/10.9734/ijpss/2024/v36i64699.
Abstract (sommario):
A field experiment was conducted at Agroforestry Research Station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, during 2019-20. The soils of the experimental field was low in organic carbon (0.24 per cent), available nitrogen (143.50 kg N/ha) and DTPA extractable iron (3.18 mg/kg), medium in available phosphorus (Olsen’s P 48.90 kg P2O5/ha), available potash (180.00 kg K2O/ha), manganese (7.8 mg/kg) and zinc (0.79 mg/kg) and high in copper content (0.61 mg/kg). An experiment consisting of six years old Agroforestry tree plantation which consisted of five multipurpose tree species (MPTs) viz., Tectona grandis, Eucalyptus camaldulensis, Gmelina arborea, Casuriana equstifolia and Melia azadiracht were designed in CRD with four replications. The experiment consisting of 96 trees per species with a plot size of 24 m × 16 m under 4 m × 4 m tree spacing. Among the above six tree species significantly the lowest BD (1.56 Mg/m3), higher WHC (27.87 per cent) and soil porosity (38.03 per cent) was recorded under Casuarinas equisetifolia tree species. Similarly the maximum mean organic carbon (0.445 per cent), available N (165.17 kg/ha), available K2O (196.26 kg/ha) and DTPA extractable iron (4.22 mg/kg) and copper (1.05 mg/kg) content were noted under Casuarina equisetifolia tree species. Whereas, the mean maximum available P2O5 (57.92 kg/ha) was noted under Tectona grandis. The mean maximum DTPA extractable manganese (8.34 mg/kg) and zinc (0.925 mg/kg) was noted under Eucalyptus camaldulensis and Melia azadiracht tree species, respectively.
39
McDonald, L., M. Van Woudenberg, B. Dorin, A. M. Adcock, R. T. McMullin e K. Cottenie. "The effects of bark quality on corticolous lichen community composition in urban parks of southern Ontario". Botany 95, n. 12 (dicembre 2017): 1141–49. http://dx.doi.org/10.1139/cjb-2017-0113.
Abstract (sommario):
Tree bark characteristics influence lichen colonization. To better understand how urban parks can be managed to maximize lichen biodiversity, we examined trees in seven parks throughout the City of Guelph in southern Ontario. We measured bark characteristics and lichen communities on four common tree species that have a wide range of pH: Acer platanoides L., Acer × freemanii E. Murray, Pinus resinosa Aiton, and Pinus strobes L. We recorded the lichen species on 99 trees, calculated the pH and fissuring of the bark, and determined the diameter at breast height (DBH) as a proxy for age. Gamma diversity on all trees included 18 lichen taxa. We used graphite bark rubbings analyzed in ImageJ 1.47v to calculate the degree of bark fissuring. We collected bark samples from each tree trunk and determined the acidity with a pH meter. Using multivariate analyses we show that lichen community composition is positively correlated with DBH and tree species, but the degree of fissuring did not have a significant effect. We could not statistically analyze pH independent of tree species, but our results suggest pH is not a significant variable. We show lichen biodiversity in urban parks can be increased by planting a variety of tree species at different ages.
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Weerathunga, Manasee, e Alexander S. Mikheyev. "Integrating host plant phylogeny, plant traits, intraspecific competition and repeated measures using a phylogenetic mixed model of field behaviour by polyphagous herbivores, the leaf-cutting ants". Journal of Tropical Ecology 36, n. 2 (17 febbraio 2020): 80–86. http://dx.doi.org/10.1017/s0266467420000012.
Abstract (sommario):
AbstractHerbivores use a wide range of factors to choose their host, including their own physiological states, physical characteristics of plants and the degree of competition. Field observations of herbivores in their native habitats provide a means for simultaneously estimating the relative importance of these factors, but statistical analysis of all these factors may be challenging. Here we used a 7-week dataset of leaf-cutting ant (Atta cephalotes) foraging in a diverse Neotropical arboretum containing 193 tree species (822 trees) to examine the relative role of tree phylogeny, territoriality and tree functional characteristics using a phylogenetic generalized least squares (PGLS) model. We observed that 54 tree species (117 trees) were foraged by the ants. This pattern was not random, but reflected known features of leaf-cutting ant foraging behaviour, such as a preference for larger trees and the decreased likelihood of foraging at the periphery of a colony’s territory. However, random effects such as tree phylogeny, the identity of individual trees and colony-specific effects explained most of the variation in foraging data. A significant phylogenetic effect on foraging likelihood (λ = 0.28), together with repeated measures of foraging on the same tree species, allowed estimation of relative palatability for each plant species. PGLS models can be flexibly scaled to include other covariates for even more complex investigation of foraging behaviour, and the link function can be modified to include the amount of plants foraged. As a result, PGLS can be used as a flexible framework for the study of LCA foraging.
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Zhang, Ju, Qingwu Hu, Hongyu Wu, Junying Su e Pengcheng Zhao. "Application of Fractal Dimension of Terrestrial Laser Point Cloud in Classification of Independent Trees". Fractal and Fractional 5, n. 1 (1 febbraio 2021): 14. http://dx.doi.org/10.3390/fractalfract5010014.
Abstract (sommario):
Tree precise classification and identification of forest species is a core issue of forestry resource monitoring and ecological effect assessment. In this paper, an independent tree species classification method based on fractal features of terrestrial laser point cloud is proposed. Firstly, the terrestrial laser point cloud data of an independent tree is preprocessed to obtain terrestrial point clouds of independent tree canopy. Secondly, the multi-scale box-counting dimension calculation algorithm of independent tree canopy dense terrestrial laser point cloud is proposed. Furthermore, a robust box-counting algorithm is proposed to improve the stability and accuracy of fractal dimension expression of independent tree point cloud, which implementing gross error elimination based on Random Sample Consensus. Finally, the fractal dimension of a dense terrestrial laser point cloud of independent trees is used to classify different types of independent tree species. Experiments on nine independent trees of three types show that the fractal dimension can be stabilized under large density variations, proving that the fractal features of terrestrial laser point cloud can stably express tree species characteristics, and can be used for accurate classification and recognition of forest species.
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Seymour, Robert S., e Laura S. Kenefic. "Influence of age on growth efficiency of Tsuga canadensis and Picea rubens trees in mixed-species, multiaged northern conifer stands". Canadian Journal of Forest Research 32, n. 11 (1 novembre 2002): 2032–42. http://dx.doi.org/10.1139/x02-120.
Abstract (sommario):
Well-known patterns in the fundamental relationship between tree-level stemwood volume increment (VINC) and projected leaf area (PLA) are examined and quantified for Tsuga canadensis (L.) Carrière (eastern hemlock) and Picea rubens Sarg. (red spruce) growing in managed, mixed-species, multiaged stands in east-central Maine, U.S.A. Both species follow a sigmoid pattern, suggesting a peak growth efficiency (GE, stemwood volume growth per unit of PLA) in mid- to upper-canopy trees with PLAs of less than half that of the largest trees sampled. Tree age negatively influenced the VINCPLA relationship in the expected manner: at a given PLA, older trees produce less stemwood than younger ones. The combined effect of leaf area and age is accurately modeled with a Weibull-like function in which the asymptote is an index of tree maturity defined as tree age relative to an estimated maximum for the species. Although previous studies have independently documented both the sigmoid relationship between VINC and PLA and the negative effect of age, their conclusions have been confounded by the strong correlation between age and mean tree PLA. This study addresses both issues simultaneously, and is the first to demonstrate a decline in GE with age independent from the effect of increasing PLA.
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Sylvia, David, Abid Alagely, Donald Kent e Roy Mecklenburg. "Mycorrhizae of Landscape Trees Produced in Raised Beds and Containers". Arboriculture & Urban Forestry 24, n. 6 (1 novembre 1998): 308–15. http://dx.doi.org/10.48044/jauf.1998.039.
Abstract (sommario):
Mycorrhizal associations provide a linkage between tree roots and the soil, thereby contributing to the tolerance of trees to environmental stresses. Little, however, is known about the mycorrhizal status or dependency of many landscape trees. The objective of this study was to quantify mycorrhizal root colonization and spore formation on a diverse collection of ornamental tree species grown in raised beds or containers at an established tree farm in central Florida. In addition, root diameters were measured to determine if there was a relationship between this parameter and mycorrhizal formation. A total of 23 tree species were sampled; 9 were present both in containers and raised beds, 6 species were present in containers only, and 8 species were present as embedded plants only. The proportion of root length colonized by mycorrhizal fungi ranged from 0% to 83%. Mean arbuscular mycorrhizal spore numbers ranged from <20 to nearly 500 spores 100 g~1 (3.5 oz~1). Mean root diameters ranged from < 500 to > 1,000 \im (0.0197 to 0.0394 in.). No relationship was found between root coarseness and mycorrhizal root colonization or sporulation. The majority of trees formed mycorrhizae of the arbuscular type. Five species in the family Pinaceae or Fagaceae had the potential to form ectomycorrhizae; however, they were poorly colonized. Future research should be directed toward understanding the importance of mycorrhizae to landscape trees, including effects on tree survival and growth and the effect of fertilizer and pesticide applications on mycorrhizal development.
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Verboom, G. Anthony, Florian C. Boucher, David D. Ackerly, Lara M. Wootton e William A. Freyman. "Species Selection Regime and Phylogenetic Tree Shape". Systematic Biology 69, n. 4 (15 gennaio 2020): 774–94. http://dx.doi.org/10.1093/sysbio/syz076.
Abstract (sommario):
Abstract Species selection, the effect of heritable traits in generating between-lineage diversification rate differences, provides a valuable conceptual framework for understanding the relationship between traits, diversification, and phylogenetic tree shape. An important challenge, however, is that the nature of real diversification landscapes—curves or surfaces which describe the propensity of species-level lineages to diversify as a function of one or more traits—remains poorly understood. Here, we present a novel, time-stratified extension of the QuaSSE model in which speciation/extinction rate is specified as a static or temporally shifting Gaussian or skewed-Gaussian function of the diversification trait. We then use simulations to show that the generally imbalanced nature of real phylogenetic trees, as well as their generally greater than expected frequency of deep branching events, are typical outcomes when diversification is treated as a dynamic, trait-dependent process. Focusing on four basic models (Gaussian-speciation with and without background extinction; skewed-speciation; Gaussian-extinction), we also show that particular features of the species selection regime produce distinct tree shape signatures and that, consequently, a combination of tree shape metrics has the potential to reveal the species selection regime under which a particular lineage diversified. We evaluate this idea empirically by comparing the phylogenetic trees of plant lineages diversifying within climatically and geologically stable environments of the Greater Cape Floristic Region, with those of lineages diversifying in environments that have experienced major change through the Late Miocene-Pliocene. Consistent with our expectations, the trees of lineages diversifying in a dynamic context are less balanced, show a greater concentration of branching events close to the present, and display stronger diversification rate-trait correlations. We suggest that species selection plays an important role in shaping phylogenetic trees but recognize the need for an explicit probabilistic framework within which to assess the likelihoods of alternative diversification scenarios as explanations of a particular tree shape. [Cape flora; diversification landscape; environmental change; gamma statistic; species selection; time-stratified QuaSSE model; trait-dependent diversification; tree imbalance.]
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Bello, Bello Musawa, Khalid Tukur, Mustapha Muhammad Sani, Isyaku Abubakar e Mukhtar Abubakar Lawal. "The Effects of Neem Tree (Azadirachta indica A. Juss) Invasion on the Growth of Indigenous Flora in Katsina State, Northwest Nigeria". UMYU Scientifica 2, n. 3 (30 settembre 2023): 142–52. http://dx.doi.org/10.56919/usci.2323.020.
Abstract (sommario):
Invasive or alien species are increasing in number, extent, and influence worldwide. They are both passengers and drivers of change, and they interact synergistically with many other facets of global change. The Neem trees have been grown successfully in all parts of Nigeria. Neem has become an invasive and naturalized species in various parts of Nigeria in quite diverse ecological and climatic conditions. The tree is adaptable to a wide range of climatic and topographic conditions. The objective of the study is to determine the effect of neem invasion on the growth of indigenous flora in Katsina state. The information on farmers' perception about Neem tree was obtained using semi semi-structured questionnaire. About 200 informants were interviewed. Direct counting of trees was conducted to determine the effect of Neem invasion on the indigenous flora. A total of 58 species of trees belonging to 47 genera within 15 families, of which family Fabaceae has the highest number of tree species, 44 affected by neem invasion in the study area. The result showed the effects of having neem in the farms. Some of the respondents believed that Neem spread easily and nothing grew near it. Others believed that it's difficult to kill and grow back easily. The result indicated a number of tree species found in farms compared to the number of farmers needed for that tree. A lot of farmers preferred indigenous trees then Neem in their farms. In conclusion, in Katsina and from casual observations in the study areas, we have found that Neem is spreading in a way characteristic of an invasive species. They are spread by birds and other animals, becoming numerous under native trees. The trees themselves may become 'weeds. Since farmers in Katsina do not like Neem in their fields, it can be considered a weed, and because it can reproduce in large quantities at a considerable distance from the parent plant, it is, by definition, an invasive plant.
46
Klein, Julian, Matthew Low, Göran Thor, Jörgen Sjögren, Eva Lindberg e Sönke Eggers. "Tree species identity and composition shape the epiphytic lichen community of structurally simple boreal forests over vast areas". PLOS ONE 16, n. 9 (17 settembre 2021): e0257564. http://dx.doi.org/10.1371/journal.pone.0257564.
Abstract (sommario):
Greatly simplified ecosystems are often neglected for biodiversity studies. However, these simplified systems dominate in many regions of the world, and a lack of understanding of what shapes species occurrence in these systems can have consequences for biodiversity and ecosystem services at a massive scale. In Fennoscandia, ~90% of the boreal forest (~21Mha) is structurally simplified with little knowledge of how forest structural elements shape the occurrence and diversity of for example epiphytic lichens in these managed forests. One form of structural simplification is the reduction of the number and frequency of different tree species. As many lichen species have host tree preferences, it is particularly likely that this simplification has a huge effect on the lichen community in managed forests. In a 40–70 years old boreal forest in Sweden, we therefore related the occurrence and richness of all observed epiphytic lichens to the host tree species and beta and gamma lichen diversity at the forest stand level to the stand’s tree species composition and stem diameter. Picea abies hosted the highest lichen richness followed by Pinus sylvestris, Quercus robur, Alnus glutinosa, Betula spp., and Populus tremula. However, P. tremula hosted twice as many uncommon species as any of the other tree species. Stand level beta and gamma diversity was twice as high on stands with four compared to one tree species, and was highest when either coniferous or deciduous trees made up 40–50% of the trees. The stem diameter was positively related to lichen richness at the tree and stand level, but negatively to beta diversity. For biodiversity, these findings imply that leaving a few trees of a different species during forest thinning is unlikely as effective as combining life-boat trees for endangered species with an even tree species mixture.
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Groen, Thomas A., Frank van Langevelde, Claudius A. D. M. van de Vijver, Navashni Govender e Herbert H. T. Prins. "Soil clay content and fire frequency affect clustering in trees in South African savannas". Journal of Tropical Ecology 24, n. 3 (maggio 2008): 269–79. http://dx.doi.org/10.1017/s0266467408004872.
Abstract (sommario):
Abstract:In this paper, we investigate which factors determine tree clustering in Southern African savannas. This was tested by measuring clustering of trees using the T-squared sampling method in plots of the Kruger National Park experimental burning programme in South Africa. Fire return interval is the main treatment in these plots, but also several auxiliary determining parameters like clay content in the soil, diameter of tree canopies, understorey composition, tree species diversity and average annual rainfall were measured while sampling. In the Kruger National Park 48 plots distributed over four different landscape types and with three different burning treatments (never, once every 3 y and annually) were sampled. First, we related the clustering of trees to these environmental variables. When looking at the most abundant species in each plot, the analysis revealed that clustering is mainly correlated with clay content in the soil. This analysis also showed that fire frequency had a positive effect on the clustering of tree species that are not very abundant. We suggest that less abundant species might be less resistant to fire and therefore adopt a mechanism of clustering to exclude grass fires under their canopy. Finally, we tested the effect of clustering on the impact of fire on trees by analysing the relationship between the distance of a tree to its nearest neighbour and its canopy diameter. We found that clustering reduces the damaging effect of fire on trees. Our study contributes to understanding of savanna functioning by showing which processes are relevant in the distribution of savanna trees.
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Liu, Bingjie, Shuxin Chen, Huaguo Huang e Xin Tian. "Tree Species Classification of Backpack Laser Scanning Data Using the PointNet++ Point Cloud Deep Learning Method". Remote Sensing 14, n. 15 (7 agosto 2022): 3809. http://dx.doi.org/10.3390/rs14153809.
Abstract (sommario):
To investigate forest resources, it is necessary to identify the tree species. However, it is a challenge to identify tree species using 3D point clouds of trees collected by light detection and ranging (LiDAR). PointNet++, a point cloud deep learning network, can effectively classify 3D objects. It is important to establish high-quality individual tree point cloud datasets when applying PointNet++ to identifying tree species. However, there are different data processing methods to produce sample datasets, and the processes are tedious. In this study, we suggest how to select the appropriate method by designing comparative experiments. We used the backpack laser scanning (BLS) system to collect point cloud data for a total of eight tree species in three regions. We explored the effect of tree height on the classification accuracy of tree species by using different point cloud normalization methods and analyzed the effect of leaf point clouds on classification accuracy by separating the leaves and wood of individual tree point clouds. Five downsampling methods were used: farthest point sampling (FPS), K-means, random, grid average sampling, and nonuniform grid sampling (NGS). Data with different sampling points were designed for the experiments. The results show that the tree height feature is unimportant when using point cloud deep learning methods for tree species classification. For data collected in a single season, the leaf point cloud has little effect on the classification accuracy. The two suitable point cloud downsampling methods we screened were FPS and NGS, and the deep learning network could provide the most accurate tree species classification when the number of individual tree point clouds was in the range of 2048–5120. Our study further illustrates that point-based end-to-end deep learning methods can be used to classify tree species and identify individual tree point clouds. Combined with the low-cost and high-efficiency BLS system, it can effectively improve the efficiency of forest resource surveys.
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Riofrío, José, Miren del Río, Douglas Maguire e Felipe Bravo. "Species Mixing Effects on Height–Diameter and Basal Area Increment Models for Scots Pine and Maritime Pine". Forests 10, n. 3 (12 marzo 2019): 249. http://dx.doi.org/10.3390/f10030249.
Abstract (sommario):
Models that incorporate known species-mixing effects on tree growth are essential tools to properly design silvicultural guidelines for mixed-species stands. Here, we developed generalized height–diameter (h-d) and basal area growth models for mixed stands of two main forest species in Spain: Scots pine (Pinus sylvestris L.) and Maritime pine (Pinus pinaster Ait.). Mixed-effects models were fitted from plot measurement and tree rings data from 726 Scots pine and 693 Maritime pine trees from mixed and pure stands in the Northern Iberian Range in Spain, with the primary objective of representing interactions between the species where they are interspersed in mixtures of varying proportions. An independent dataset was used to test the performance of the h-d models against models previously fitted for monospecific stands of both species. Basal area increment models were evaluated using a 10-fold block cross-validation procedure. We found that species mixing had contrasting effects on the species in both models. In h-d models, the species-mixing proportion determined the effect of species interactions. Basal area growth models showed that interspecific competition was influential only for Maritime pine; however, these effects differed depending on the mode of competition. For Scots pine, tree growth was not restricted by interspecies competition. The combination of mixed-effect models and the inclusion of parameters expressing species-mixing enhanced estimates of tree height and basal area growth compared with the available models previously developed for pure stands. Although the species-mixing effects were successfully represented in the fitted models, additional model components for accurately simulating the stand dynamics of mixtures with Scots pine and Maritime pine and other species mixtures require similar model refinements. Upon the completion of analyses required for these model refinements, the degree of improvement in simulating growth in species mixtures, including the effects of different management options, can be evaluated.
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Lemoine, Nathan P., Deron E. Burkepile e John D. Parker. "Insect herbivores increase mortality and reduce tree seedling growth of some species in temperate forest canopy gaps". PeerJ 5 (21 marzo 2017): e3102. http://dx.doi.org/10.7717/peerj.3102.
Abstract (sommario):
Insect herbivores help maintain forest diversity through selective predation on seedlings of vulnerable tree species. Although the role of natural enemies has been well-studied in tropical systems, relatively few studies have experimentally manipulated insect abundance in temperate forests and tracked impacts over multiple years. We conducted a three-year experiment (2012–2014) deterring insect herbivores from seedlings in new treefall gaps in deciduous hardwood forests in Maryland. During this study, we tracked recruitment of all tree seedlings, as well as survivorship and growth of 889 individual seedlings from five tree species:Acer rubrum,Fagus grandifolia,Fraxinusspp.,Liriodendron tulipifera, andLiquidambar styraciflua. Insect herbivores had little effect on recruitment of any tree species, although there was a weak indication that recruitment ofA. rubrumwas higher in the presence of herbivores. Insect herbivores reduced survivorship ofL. tulipifera, but had no significant effects onA. rubrum,Fraxinusspp.,F. grandifolia, orL. styraciflua. Additionally, insects reduced growth rates of early pioneer speciesA. rubrum,L. tulipifera, andL. styraciflua, but had little effect on more shade-tolerant speciesF. grandifoliaandFraxinusspp. Overall, by negatively impacting growth and survivorship of early pioneer species, forest insects may play an important but relatively cryptic role in forest gap dynamics, with potentially interesting impacts on the overall maintenance of diversity.